1. Field of the Invention
The disclosures herein generally relate to a roll retainer and an image forming apparatus.
2. Description of the Related Art
Image forming apparatuses having rolls of printing media (roll-type printing medium) generally have a roll retainer (a retaining mechanism) to accommodate different cardboard tubes (difference in inner diameters of the hollow shafts of the rolls).
An example of a related art retainer includes an abutment member configured to be in contact with an inner peripheral surface of the hollow shaft rolls in an axial direction of the roll-type medium as a fulcrum to be expanded in a roll diameter direction, thereby adapting to the differences in the inner diameters of the cardboard tube (e.g., Japanese Laid-open Patent Publication No. 2007-290865, hereinafter referred to as “Patent Document 1”).
Further, another example related art retainer is configured to regulate a retractable position of a supporting member (e.g., Japanese Laid-open Patent Publication No. 2013-100154, hereinafter referred to as “Patent Document 2”). In this example, the retractable position of the supporting member is regulated by allowing the supporting member to be in contact with an inner peripheral surface of the core tube and an outer peripheral surface of a shaft center of the retaining member when a diameter of the roll-type medium is large, and moving the supporting member to be in contact with an end part of the core tube when the diameter of the roll-type medium is small.
However, in the configuration of Patent Document 1, since the abutment member expands in the axial direction of the roll-type medium as a fulcrum, the expanded abutment member is susceptible to breakage by rotation in circumferential direction.
Further, in the configuration of Patent Document 2, it is not possible to simultaneously move two or more abutment members, and the roll-type medium may be attached to the retaining mechanism without moving some of the abutment members. As a result, the roll-type medium may be attached to the retaining mechanism unsteadily.